Provided by: erlang-dialyzer_22.0.7+dfsg-1_amd64 bug

NAME

       dialyzer - Dialyzer, a DIscrepancy AnaLYZer for ERlang programs.

DESCRIPTION

       Dialyzer  is  a  static  analysis  tool  that  identifies  software discrepancies, such as
       definite type errors, code that has become dead  or  unreachable  because  of  programming
       error, and unnecessary tests, in single Erlang modules or entire (sets of) applications.

       Dialyzer  starts  its  analysis  from  either  debug-compiled BEAM bytecode or from Erlang
       source code. The file and  line  number  of  a  discrepancy  is  reported  along  with  an
       indication of what the discrepancy is about. Dialyzer bases its analysis on the concept of
       success typings, which allows for sound warnings (no false positives).

USING DIALYZER FROM THE COMMAND LINE

       Dialyzer has a command-line version for automated  use.  This  section  provides  a  brief
       description  of the options. The same information can be obtained by writing the following
       in a shell:

       dialyzer --help

       For more details about the operation of Dialyzer, see section  Using Dialyzer from the GUI
       in the User's Guide.

       Exit status of the command-line version:

         0:
           No problems were found during the analysis and no warnings were emitted.

         1:
           Problems were found during the analysis.

         2:
           No problems were found during the analysis, but warnings were emitted.

       Usage:

       dialyzer [--add_to_plt] [--apps applications] [--build_plt]
                [--check_plt] [-Ddefine]* [-Dname] [--dump_callgraph file]
                [files_or_dirs] [--fullpath] [--get_warnings] [--gui] [--help]
                [-I include_dir]* [--no_check_plt] [--no_indentation] [--no_native]
                [--no_native_cache] [-o outfile] [--output_plt file] [-pa dir]*
                [--plt plt] [--plt_info] [--plts plt*] [--quiet] [-r dirs]
                [--raw] [--remove_from_plt] [--shell] [--src] [--statistics]
                [--verbose] [--version] [-Wwarn]*

   Note:
       * denotes that multiple occurrences of the option are possible.

       Options:

         --add_to_plt:
           The  PLT  is extended to also include the files specified with -c and -r. Use --plt to
           specify which PLT to start from, and --output_plt to specify where  to  put  the  PLT.
           Notice that the analysis possibly can include files from the PLT if they depend on the
           new files. This option only works for BEAM files.

         --apps applications:
           This option is typically used when building or modifying a PLT as in:

         dialyzer --build_plt --apps erts kernel stdlib mnesia ...

           to  refer  conveniently  to  library  applications  corresponding  to  the  Erlang/OTP
           installation.  However, this option is general and can also be used during analysis to
           refer to Erlang/OTP applications. File or directory names can also be included, as in:

         dialyzer --apps inets ssl ./ebin ../other_lib/ebin/my_module.beam

         --build_plt:
           The analysis starts from an empty PLT and creates a new one from the  files  specified
           with  -c  and  -r.  This option only works for BEAM files. To override the default PLT
           location, use --plt or --output_plt.

         --check_plt:
           Check the PLT for consistency and rebuild it if it is not up-to-date.

         -Dname (or -Dname=value):
           When analyzing from source, pass the define to Dialyzer. (**)

         --dump_callgraph file:
           Dump the call graph into the specified file whose format is determined by the filename
           extension.  Supported  extensions  are: raw, dot, and ps. If something else is used as
           filename extension, default format .raw is used.

         files_or_dirs (for backward compatibility also as -c files_or_dirs):
           Use Dialyzer from the command line  to  detect  defects  in  the  specified  files  or
           directories containing .erl or .beam files, depending on the type of the analysis.

         --fullpath:
           Display the full path names of files for which warnings are emitted.

         --get_warnings:
           Make  Dialyzer emit warnings even when manipulating the PLT. Warnings are only emitted
           for files that are analyzed.

         --gui:
           Use the GUI.

         --help (or -h):
           Print this message and exit.

         -I include_dir:
           When analyzing from source, pass the include_dir to Dialyzer. (**)

         --no_check_plt:
           Skip the PLT check when running Dialyzer. This is useful when working  with  installed
           PLTs that never change.

         --no_indentation:
           Do  not  insert  line  breaks  in  types,  contracts,  and Erlang Code when formatting
           warnings.

         --no_native (or -nn):
           Bypass the native code compilation of  some  key  files  that  Dialyzer  heuristically
           performs  when  dialyzing many files. This avoids the compilation time, but can result
           in (much) longer analysis time.

         --no_native_cache:
           By  default,  Dialyzer  caches  the  results  of  native  compilation   in   directory
           $XDG_CACHE_HOME/erlang/dialyzer_hipe_cache.  XDG_CACHE_HOME  defaults to $HOME/.cache.
           Use this option to disable caching.

         -o outfile (or --output outfile):
           When using Dialyzer from the command line, send the analysis results to the  specified
           outfile rather than to stdout.

         --output_plt file:
           Store the PLT at the specified file after building it.

         -pa dir:
           Include  dir  in  the  path  for Erlang. This is useful when analyzing files that have
           -include_lib() directives.

         --plt plt:
           Use the specified PLT as the initial PLT. If the PLT was built during setup, the files
           are checked for consistency.

         --plt_info:
           Make  Dialyzer print information about the PLT and then quit. The PLT can be specified
           with --plt(s).

         --plts plt*:
           Merge the specified PLTs to create the initial PLT. This requires that  the  PLTs  are
           disjoint  (that  is,  do not have any module appearing in more than one PLT). The PLTs
           are created in the usual way:

         dialyzer --build_plt --output_plt plt_1 files_to_include
         ...
         dialyzer --build_plt --output_plt plt_n files_to_include

           They can then be used in either of the following ways:

         dialyzer files_to_analyze --plts plt_1 ... plt_n

           or

         dialyzer --plts plt_1 ... plt_n -- files_to_analyze

           Notice the -- delimiter in the second case.

         --quiet (or -q):
           Make Dialyzer a bit more quiet.

         -r dirs:
           Same as files_or_dirs, but the specified  directories  are  searched  recursively  for
           subdirectories  containing  .erl  or  .beam  files  in  them, depending on the type of
           analysis.

         --raw:
           When using Dialyzer from the command line, output the  raw  analysis  results  (Erlang
           terms)  instead of the formatted result. The raw format is easier to post-process (for
           example, to filter warnings or to output HTML pages).

         --remove_from_plt:
           The information from the files specified with -c and  -r  is  removed  from  the  PLT.
           Notice that this can cause a reanalysis of the remaining dependent files.

         --shell:
           Do not disable the Erlang shell while running the GUI.

         --src:
           Override the default, which is to analyze BEAM files, and analyze starting from Erlang
           source code instead.

         --statistics:
           Print information about the progress of execution  (analysis  phases,  time  spent  in
           each, and size of the relative input).

         --verbose:
           Make Dialyzer a bit more verbose.

         --version (or -v):
           Print the Dialyzer version and some more information and exit.

         -Wwarn:
           A  family  of options that selectively turn on/off warnings. (For help on the names of
           warnings, use dialyzer -Whelp.) Notice that the options can also be specified  in  the
           file  with a -dialyzer() attribute. For details, see section Requesting or Suppressing
           Warnings in Source Files.

   Note:
       ** options -D and -I work both from the command line and in the Dialyzer GUI;  the  syntax
       of defines and includes is the same as that used by erlc(1).

       Warning options:

         -Werror_handling (***):
           Include warnings for functions that only return by an exception.

         -Wno_behaviours:
           Suppress  warnings  about behavior callbacks that drift from the published recommended
           interfaces.

         -Wno_contracts:
           Suppress warnings about invalid contracts.

         -Wno_fail_call:
           Suppress warnings for failing calls.

         -Wno_fun_app:
           Suppress warnings for fun applications that will fail.

         -Wno_improper_lists:
           Suppress warnings for construction of improper lists.

         -Wno_match:
           Suppress warnings for patterns that are unused or cannot match.

         -Wno_missing_calls:
           Suppress warnings about calls to missing functions.

         -Wno_opaque:
           Suppress warnings for violations of opacity of data types.

         -Wno_return:
           Suppress warnings for functions that will never return a value.

         -Wno_undefined_callbacks:
           Suppress warnings  about  behaviors  that  have  no  -callback  attributes  for  their
           callbacks.

         -Wno_unused:
           Suppress warnings for unused functions.

         -Wrace_conditions (***):
           Include  warnings  for  possible  race conditions. Notice that the analysis that finds
           data races performs intra-procedural data flow analysis and can sometimes  explode  in
           time. Enable it at your own risk.

         -Wunderspecs (***):
           Warn  about underspecified functions (the specification is strictly more allowing than
           the success typing).

         -Wunknown (***):
           Let warnings about unknown functions and types affect the exit status of the  command-
           line version. The default is to ignore warnings about unknown functions and types when
           setting the exit status. When using  Dialyzer  from  Erlang,  warnings  about  unknown
           functions and types are returned; the default is not to return these warnings.

         -Wunmatched_returns (***):
           Include  warnings  for  function calls that ignore a structured return value or do not
           match against one of many possible return value(s).

       The following options are also available, but their  use  is  not  recommended  (they  are
       mostly for Dialyzer developers and internal debugging):

         -Woverspecs (***):
           Warn  about  overspecified functions (the specification is strictly less allowing than
           the success typing).

         -Wspecdiffs (***):
           Warn when the specification is different than the success typing.

   Note:
       *** denotes options that turn on warnings rather than turning them off.

USING DIALYZER FROM ERLANG

       Dialyzer can be used directly from Erlang. Both the GUI and the command-line versions  are
       also  available.  The  options  are  similar  to the ones given from the command line, see
       section  Using Dialyzer from the Command Line.

REQUESTING OR SUPPRESSING WARNINGS IN SOURCE FILES

       Attribute -dialyzer() can be used for turning off  warnings  in  a  module  by  specifying
       functions  or warning options. For example, to turn off all warnings for the function f/0,
       include the following line:

       -dialyzer({nowarn_function, f/0}).

       To turn off warnings for improper lists, add the following line to the source file:

       -dialyzer(no_improper_lists).

       Attribute -dialyzer() is allowed after function declarations. Lists of warning options  or
       functions are allowed:

       -dialyzer([{nowarn_function, [f/0]}, no_improper_lists]).

       Warning options can be restricted to functions:

       -dialyzer({no_improper_lists, g/0}).

       -dialyzer({[no_return, no_match], [g/0, h/0]}).

       For help on the warning options, use dialyzer -Whelp. The options are also enumerated, see
       function gui/1 below (WarnOpts).

   Note:
       Warning option -Wrace_conditions has no effect when set in source files.

       Attribute -dialyzer() can also be used for turning on warnings. For example, if  a  module
       has been fixed regarding unmatched returns, adding the following line can help in assuring
       that no new unmatched return warnings are introduced:

       -dialyzer(unmatched_returns).

EXPORTS

       format_warning(Msg) -> string()

              Types:

                 Msg = {Tag, Id, msg()}
                   See run/1.

              Get a string from warnings as returned by run/1.

       format_warning(Msg, Options) -> string()

              Types:

                 Msg = {Tag, Id, msg()}
                   See run/1.
                 Options = [{indent_opt, boolean()}]

              Get a string from warnings as returned by run/1.

              If indent_opt is set  to  true  (default),  line  breaks  are  inserted  in  types,
              contracts, and Erlang code to improve readability.

       gui() -> ok | {error, Msg}
       gui(OptList) -> ok | {error, Msg}

              Types:

                 OptList
                   See below.

              Dialyzer GUI version.

              OptList  :: [Option]
              Option   :: {files,          [Filename :: string()]}
                        | {files_rec,      [DirName :: string()]}
                        | {defines,        [{Macro :: atom(), Value :: term()}]}
                        | {from,           src_code | byte_code}
                                             %% Defaults to byte_code
                        | {init_plt,       FileName :: string()}
                                             %% If changed from default
                        | {plts,           [FileName :: string()]}
                                             %% If changed from default
                        | {include_dirs,   [DirName :: string()]}
                        | {output_file,    FileName :: string()}
                        | {output_plt,     FileName :: string()}
                        | {check_plt,      boolean()},
                        | {analysis_type,  'succ_typings' |
                                           'plt_add' |
                                           'plt_build' |
                                           'plt_check' |
                                           'plt_remove'}
                        | {warnings,       [WarnOpts]}
                        | {get_warnings,   bool()}

              WarnOpts :: error_handling
                        | no_behaviours
                        | no_contracts
                        | no_fail_call
                        | no_fun_app
                        | no_improper_lists
                        | no_match
                     | no_missing_calls
                        | no_opaque
                     | no_return
                        | no_undefined_callbacks
                        | no_unused
                        | race_conditions
                        | underspecs
                        | unknown
                        | unmatched_returns
                        | overspecs
                        | specdiffs

       plt_info(string()) -> {'ok', [{atom(), any()}]} | {'error', atom()}

              Returns information about the specified PLT.

       run(OptList) -> Warnings

              Types:

                 OptList
                   See gui/0,1.
                 Warnings
                   See below.

              Dialyzer command-line version.

              Warnings :: [{Tag, Id, Msg}]
              Tag      :: 'warn_behaviour'
                        | 'warn_bin_construction'
                        | 'warn_callgraph'
                        | 'warn_contract_not_equal'
                        | 'warn_contract_range'
                        | 'warn_contract_subtype'
                        | 'warn_contract_supertype'
                        | 'warn_contract_syntax'
                        | 'warn_contract_types'
                        | 'warn_failing_call'
                        | 'warn_fun_app'
                        | 'warn_matching'
                        | 'warn_non_proper_list'
                        | 'warn_not_called'
                        | 'warn_opaque'
                        | 'warn_race_condition'
                        | 'warn_return_no_exit'
                        | 'warn_return_only_exit'
                        | 'warn_umatched_return'
                        | 'warn_undefined_callbacks'
                        | 'warn_unknown'
              Id  = {File :: string(), Line :: integer()}
              Msg = msg() -- Undefined